EP0865573A1

EP0865573A1 - Injection valve stem

Info

Publication number: EP0865573A1
Application number: EP97939954A
Authority: EP
Inventors: Ferdinand Reiter
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1996-10-10
Filing date: 1997-08-16
Publication date: 1998-09-23
Anticipated expiration: 2017-08-16
Also published as: EP0865573B1; KR19990071854A; JP2000502422A; US6390392B1; DE19641785C2; DE19641785A1; DE59709782D1; WO1998015733A1

Abstract

The inventive valve stem (22) is characterized in that a junction member (24) connecting a tie element (20) to a valve closing part (23) is in the form of a plastic bar. In order to securely assemble the various stem components, the junction member (24) is form-fitted both to the tie element (20) and the valve closing part (23). The junction member (24) and the valve closing part (23) are so form-fit to each other that the corresponding areas, of larger and smaller diameters, are in gear. The valve stem is particularly fitted to injection valves used in the injection system of engines based on internal combustion, mixture compression and spark ignition.

Description

Valve needle for an injection valve

State of the art

The invention relates to a valve needle for an injection valve according to the preamble of the main claim. From DE-OS 40 08 675 a valve needle for an electromagnetically actuated valve is already known, which consists of an armature, a valve closing member and the armature with the z. B. connecting spherical valve closing sleeve-shaped connecting tube. The individual sections are made separately

Items that are only by means of joining processes, e.g. B. by laser welding. The armature encompasses the connecting tube completely radially and at least partially axially, since the connecting tube is fastened in a continuous longitudinal opening of the armature. The

The connecting tube itself also has a continuous inner longitudinal opening, in which fuel can flow in the direction of the valve closing element, which then runs near the valve closing element through radially running in the wall of the connecting tube

Cross openings emerges. The fuel flow therefore takes place first inside the valve needle and only leaves the valve needle towards the valve seat.

Also known from US Pat. No. 4,610,080 is a valve needle in a fuel injector, which is designed in two parts. A cup-shaped armature is firmly connected to an elongated, rod-shaped, metal connecting part, at the downstream end of which a ball-section-shaped valve closing section is formed directly. A connection piece, which has an inner opening, runs out of the base part of the cup-shaped anchor. The inner opening is provided with a plurality of axially successive grooves, so that areas of larger and smaller diameters result in the opening in succession. The

The connecting part projects with its end opposite the valve closing section, which is also grooved, into the opening of the connecting piece, as a result of which both metal components are connected to one another in a form-fitting manner.

From DE-OS 195 03 224 a three-part valve needle for electromagnetically actuated injection valves is also known, which is formed by a tubular armature, a sleeve-shaped connecting part and a spherical valve closing body. The connecting part made of a plastic engages behind locking elements on the outer circumference of the armature for firmly connecting the armature and the connecting part. The downstream end of the connecting part has a dome-shaped recess in which the spherical valve closing body is snapped or clipped. The lower part of the recess is so elastic that it widens when the valve closing body is pressed in, in order then to enclose the valve closing body closely. Advantages of the invention

The valve needle according to the invention with the characterizing features of the main claim has the advantage that it can be manufactured in a particularly simple and inexpensive manner. Each individual component of the valve needle, namely an armature, a valve closing element and a connecting part connecting the armature to the valve closing element, can be very simple

Contouring can be produced and processed particularly cost-effectively. The connecting part made of a plastic ensures that the valve needle is lighter than metal valve needles. Particularly in the case of injection valves with a far upstream spray point, in which relatively elongated valve needles are used, very good dynamic valve properties can still be achieved by such a design of the connecting part. The damping properties of the plastic also ensure reduced noise. Advantageously, the connecting part shaped according to the invention and the valve closing element have only a small outside diameter, so that an injection valve with such a valve needle can be made very slim. The form-fitting designed according to the invention

The connection between the connecting part and the valve closing element is particularly easy to achieve and nevertheless very secure. A loosening of the connection during the axial movement of the valve needle within the injection valve is completely excluded with this connection technology.

The measures listed in the subclaims permit advantageous developments and improvements of the valve needle specified in the main claim. A particular advantage is the use of inexpensive rod material for the connecting part, which can be very easily brought to an exact length for use on the valve needle according to a desired valve length. In this way, valve needles for injection valves that have a far-reaching spray point can be shaped very easily. The connecting part, which is made of solid plastic, has the advantages of a small outer diameter, since there are no internal flow openings, and of a resulting low mass. The very slim valve needle enables a particularly narrow construction of the injection valve, in particular a reduction in the size of the valve seat body compared to known injection valves.

drawing

An embodiment of the invention is shown in simplified form in the drawing and explained in more detail in the following description. 1 shows it

Injection valve with a valve needle according to the invention, FIG. 1 a shows a detail from FIG. 1 in the area of a guide disk for the valve needle and FIG. 2 shows a valve needle in a modified scale.

Description of the embodiment

The valve shown in FIG. 1, for example, in the form of an electromagnetically actuated injection valve for fuel injection systems of mixture-compressing, spark-ignited internal combustion engines has a tubular core 2, which is surrounded by a magnetic coil 1 and serves as a fuel inlet connection, as a so-called inner pole. A coil former 3 takes up a winding of the magnetic coil 1 and, in conjunction with the core 2, enables one in particular compact design of the injection valve in the area of the solenoid coil 1.

With a lower core end 9 of the core 2, a tubular, metallic connecting part 12 is tightly connected, for example by welding, concentrically to a longitudinal valve axis 10 and partially surrounds the core end 9 axially. Starting from the lower end of the connecting part 12, an elongated, thin-walled, sleeve-shaped valve seat support 16 extends, which is tight and tight with the

Connection part 12 is connected and has a clearly superior spray point due to its relatively large axial extent. Near the core end 9, the connecting part 12 has a magnetic throttle point 13, which is characterized by a wall thickness which is substantially smaller than the wall thicknesses of the other sections of the connecting part 12. Non-magnetic intermediate parts that are usually used can thus be dispensed with.

In the valve seat support 16, which also serves as a connecting part and represents a thin-walled sleeve, there is a longitudinal opening 17 which is concentric with the longitudinal valve axis 10 and on the wall of which an optionally insertable, also elongate, sleeve-shaped insulation element 18 is tight. The

Insulating element 18 made of plastic extends over most of the axial extent of the connecting part 12 and the valve seat carrier 16 between a cup-shaped armature 20 and a valve seat body 21. By means of an interference fit, the insulating element 18, which mainly serves for thermal insulation, is in the valve seat carrier 16 z . B. firmly pressed. In the sleeve-shaped insulation element 18, an inner longitudinal opening 19, which runs concentrically to the longitudinal valve axis 10, is again provided. In the longitudinal opening 19 is one Massively formed valve needle 22 according to the invention arranged, which at its downstream end a z. B. has a cylindrical valve closing element 23. The entire valve needle 22 is formed by the armature 20, the valve closing element 23 and an elongated, rod-shaped connecting part 24 connecting the armature 20 and the valve closing element 23.

The z. B. made of non-magnetic steel, but also made of a magnetic ferritic material valve seat carrier 16 encloses in addition to the lower end of the connecting part 12 and at its opposite end the valve seat body 21 and a spray plate 25 attached to it. With the elongated design of the valve seat carrier 16 is the Injection point of the injection valve is upstream or far ahead. In the usual installation positions of injection valves in internal combustion engines, this means that the injection valve with its downstream end and thus with its metering and spraying area clearly extends into the intake pipe. As a result, targeted spraying onto one or more inlet valves largely avoids wetting the wall of the intake pipe and, as a result, reduces the exhaust gas emission of the internal combustion engine.

The injection valve is actuated in a known manner, electromagnetically in the injection valve shown in FIG. The electromagnetic circuit with the magnet coil 1, the core 2 and the armature 20 serves for the axial movement of the valve needle 22 and thus for opening against the spring force of a return spring 26 or closing the injection valve. The cup-shaped armature 20, for example, is facing away from the valve closing element 23 End 28 of the connecting part 24 firmly connected and aligned with the core 2. In the downstream core 2 opposite end of the valve seat support 16 is in the longitudinal opening 17 of the z. B. cylindrical valve seat body 21, which has a fixed valve seat 31, tightly mounted by welding.

For guiding the valve closing element 23 during the axial movement of the valve needle 22 along the longitudinal valve axis 10, a z. B. on an upper, the spray orifice plate 25 facing end face 32 of the valve seat body 21 attached guide plate 33. Der

Armature 20 is guided during the axial movement in the connecting part 12, particularly in the area of the magnetic throttle point 13. On the outer circumference of the armature 20 z. B. a specially designed guide surface may be provided. The largely cylindrical valve closing element 23, facing the valve seat 31 and having a contour of a spherical section, interacts with the valve seat 31 of the valve seat body 21 that tapers in the direction of the truncated cone. On its end facing away from the guide disk 33, the valve seat body 21 with the z. B. pot-shaped spray plate 25 firmly connected. The spray hole disk 25 has at least one, for example four, spray openings formed by eroding, stamping or etching. A holding edge of the spray hole disk 25 is conically bent outwards so that it bears against the inner wall of the valve seat carrier 16 determined by the longitudinal opening 17, with radial pressure being present. The spray plate 25 is tightly connected to the wall of the valve seat carrier 16, for example by welding.

The insertion depth of the valve seat body 21 determines the size of the stroke of the valve needle 22. The one end position of the valve needle 22 is when the valve is not energized Solenoid 1 is fixed by the valve closing element 23 resting on the valve seat 31, while the other end position of the valve needle 22 results when the magnet coil 1 is excited by the armature 20 resting on the core end 9. The magnet coil 1 is surrounded by at least one guide element 38, which is designed, for example, as a bracket and serves as a ferromagnetic element, which at least partially surrounds the magnet coil 1 in the circumferential direction. The injection valve is largely enclosed outside the valve seat carrier 16 with a plastic encapsulation 40, which includes, for example, an injection molded electrical connector 41.

A section of the injection valve shown in FIG. 1 in the region of the guide disk 33 is shown enlarged in FIG. The guide disk 33 is used for radial guidance of the valve needle 22 during its axial movement in the longitudinal opening 17 or 19 to avoid excessive wear on the valve seat 31 and asymmetrical flow conditions between the valve seat 31 and the spray openings in the spray hole disk 25. In the circular guide disk 33, a central through hole 43 is provided, which has a slightly larger diameter than the outer diameter of the valve closing element 23 of the valve needle 22. These dimensional differences lead to a minimal play of approx. 10 μm. Outside the through hole 43, a plurality of passage openings 44 are introduced in the guide disk 33, which guarantee an unimpeded flow against the valve seat 31. The passage openings 44 can also be chosen to be so small (eg <60 μm) that they also perform a filter function.

FIG. 2 shows the valve needle 22 in which is composed of armature 20, connecting part 24 and valve closing element 23 different scale as a single component. The cup-shaped armature 20 has an axially extending, circumferential jacket part 46 and a flat bottom part 47 lying perpendicular to the longitudinal axis 2 of the valve. In the bottom part 47 of the armature 20 are at least one, for. B. three or four

Through openings 48 are provided, through which the fuel flows in the direction of the valve seat 31. The fluid, in particular a fuel, flows downstream of the through openings 48 along the outer circumference of the connecting part 24 in the longitudinal opening 19. In addition, a central opening 49 is formed in the bottom part 47, through which the connecting part 24 extends with its end 28. The armature 20, which is made of a soft magnetic material, is surface-treated and wear-resistant on its upper end face 50 facing away from the valve closing element 23 and serving as a stop, or on the outer circumference of the jacket part 46, e.g. B. chrome-plated.

The connecting part 24 has at its upper, with the

Anchor 20 connected end 28 a z. B. circumferential annular groove 52, the groove base of the annular groove 52 having a smaller outer diameter than the immediately upstream and downstream of the annular groove 52 following areas of the rod-shaped connecting part 24. The annular groove 52 has an axial extent which is approximately the thickness of the bottom part 47 of the armature 20th corresponds, since the bottom part 47 engages in a form-fitting manner in the annular groove 52, so that the diameter of the groove base of the annular groove 52 and the diameter of the opening 49 of the armature 20 are the same size. The end 28 of

The connecting part 24 is designed such that it still protrudes a short distance into the interior of the armature 20. The end 28 of the connecting part 24 protrudes into the return spring 26, which rests on an inner end face 53 of the base part 47 outside the central opening 49, and thus for centering the return spring 26. The end 28 of the connecting part 24, which is partially surrounded by the return spring 26, has z. B. a circumferential chamfer 54. The connecting part 24 consists of a plastic, the production for example by means of

Injection molding takes place. The connection part 24 is introduced into the opening 49 of the armature 20, for example, by being pressed in, pressed in or in a hot riveting process.

At its lower end 56 facing away from the armature 20, the connecting part 24 has an inner, blind hole-like opening 57, which runs concentrically to the longitudinal axis 10 of the valve or to the longitudinal axis of the valve needle 22, and into which the bolt-like valve closing element 23 is fitted. A firm and positive connection between the connecting part 24 and the valve closing element 23 is achieved in that the valve closing element 23 is pressed into the opening 57. The opening 57 has a plurality of circumferential, successive but 58 spaced apart grooves 58 over its axial extent. The opening 57 is thus alternately configured with a plurality of axially successive regions of larger and smaller diameters. Since the valve closing element 23 is formed on its upper section 59, which engages in the connecting part 24, with a negative structure to the opening 57, that is, it also has regions of larger and smaller diameters alternating, a dimensionally accurate, secure positive locking of the valve closing element 23 in the opening 57 is guaranteed.

The form-fitting section 59 of the valve closing element 23 embedded in the connecting part 24 ends away from the armature 20 at a lower shoulder 60, from which the valve closing element 23 is formed downstream with a larger diameter than that of the section 59 and the z. B. on the lower end face 61 of the connecting part 24. The downstream of paragraph 60 following, very precisely manufactured area of the z. B. made of stainless, hardened steel valve closing element 23, as already mentioned, in the through hole 43

Guide disc 33 out. In this area located downstream of the shoulder 60, the valve closing element 23 has, for example, a smaller outer diameter than the connecting part 24 over the largest part of its axial extent.

The positive connection of the valve closing element 23 and the connecting part 24 is achieved, for example, by pressing or pushing the valve closing element 23 into the opening 57. The valve closing element 23 can, however, also be extrusion-coated directly in the plastic injection molding process for producing the connecting part 24 as an insert. Furthermore, a snap-in of the valve closing element 23 is conceivable, the areas of smaller diameter of the opening 57 e.g. are chamfered, so that several sawtooth-like sections result in succession in the opening 57. A further possibility of introducing the valve closing element 23 is that the valve closing element 23 is heated and sunk into the opening 57. In addition, the valve closing element 23 can be subjected to ultrasound, as a result of which heating occurs, so that the plastic of the connecting part 24 near the opening 57 is partially melted when the valve closing element 23 is inserted. After cooling, there is a positive connection.

Claims

claims

1.valve needle for an injection valve, in particular for an electromagnetically actuated injection valve for fuel injection systems of internal combustion engines, which has a core, a magnetic coil and a fixed valve seat with which the valve needle, which consists of an armature, a connecting part made of plastic and a metal valve closing element, cooperates, the connecting part connecting the anchor to the

Valve closing element connects, characterized in that, starting from its lower end face (61), the connecting part (24) has an opening (57) which runs in the direction of the armature (20) and has a base and has at least two successive regions of different diameters into which the Valve closing element (23) engages with a section (59) in a form-fitting manner.

2. Valve needle according to claim 1, characterized in that the valve closing element (23) is designed like a bolt.

3. Valve needle according to claim 1 or 2, characterized in that in the opening (57) of the connecting part (24) engaging section (59) of the Valve closing element (23) is formed with at least two successive areas of different diameters.

4. Valve needle according to claim 1, characterized in that the regions of larger diameter in the opening (57) of the connecting part (24) are circumferential grooves (58).

5. Valve needle according to one of the preceding claims, characterized in that the valve closing element (23) has a shoulder (60) on its outer circumference, with which the valve closing element (23) abuts the lower end face (61) of the connecting part (24), wherein the section (59) protruding from the shoulder (60) into the opening (57) has a smaller diameter than the part of the valve closing element (23) lying outside the opening (57).

6. Valve needle according to one of the preceding claims, characterized in that the connecting part (24) is shaped in the form of a rod made of solid plastic.

7. Valve needle according to claim 1, characterized in that the armature (20) is cup-shaped with a jacket part (46) and a bottom part (47), wherein in the bottom part (47) at least one through opening (48) for a fluid and a Opening (49) through which the connecting part (24) extends, are provided.

8. Valve needle according to claim 7, characterized in that on the circumference of the armature (20) facing end (28) of the

Connecting part (24), a circumferential annular groove (52) is introduced into which the bottom part (47) of the armature (20) engages with the wall of the opening (49) in a form-fitting manner.